1. Field of the Invention
The present invention relates to a wireless communication system. More particularly, it relates to a wireless communication system for an image display system in which a wireless signal is transmitted and plural receivers can receive the wireless signal.
2. Description of Related Art
An image display system has recently realized increase in the flexibility in a system configuration by separating an image display mechanism. For example, various kinds of image display apparatuses each constituted of a display element such as a plasma display panel and a liquid crystal panel and image signal output apparatus having a tuner function, a recording medium reproduction function, and the like are separately provided in the image display system. In such the image display system, user's desired image display apparatus and the image signal output apparatus are connected with each other so that the increase in the flexibility in a system configuration can be realized.
However, when the image display apparatus and the image signal output apparatus are separately provided, it may be required to connect those apparatuses to each other using a cable, thereby limiting flexibility of a layout for the apparatuses. Exposure of the cable is not much to look at. In order to resolve such an issue, a super high-definition image or a high-definition motion image is transmitted between the image display apparatus and the image signal output apparatus using a wireless signal.
It is noted that since a very high transmission speed may be required when such the super high-definition image or the high-definition motion image is transmitted using a wireless signal, an extremely high frequency band such as millimetric-wave is used. Thus, if a communication is performed using such the extremely high frequency band, electric wave thereof goes strongly straight ahead and a high-gain antenna system is use to establish communication effectively with less transmission power. This eliminates a communication utilizing diffraction or reflection of the electric wave. For example, in a wireless communication system shown in FIG. 1, an informational signal generated in a transmission signal generation unit 1 is transmitted from an antenna of a transmission unit 2 using a wireless signal. An antenna of a reception unit 3 then receives the wireless signal. Received-signal-processing unit 4 performs any processing on the informational signal given therefrom. In such the wireless communication system, if any person 5 enters into a communication path for the wireless signal, he or she may block the wireless signal to stop the wireless communication. Alternatively, if the transmission unit 2 and the reception unit 3 are positioned to prevent the wireless signal from being blocked, installation positions for them are limited. For example, the transmission unit 2 and the reception unit 3 may have to be installed near a ceiling.
Plural pairs of the transmission unit 2 and the reception unit 3 are provided as shown in FIG. 2 so that if the communication signal is blocked in a communication path, it is possible to prevent the communication from being blocked by using the other communication path. Japanese Unexamined Patent Publication No. 2001-44900 discloses a wireless communication system utilizing a method for using such the plural communication paths. In this publication, a wireless communication system with an antenna diversity using plural transmission antennas, for example, is disclosed.